AIM:-
- This test is done to determine specific gravity of aggregates pycnometer method.
REFERANCE:-
- IS : 2386 (Part 3): Method of test of aggregate for concrete, specific gravity.
- IS : 2430 - Method of sampling of aggregate.
TEST EQUIPMENT:-
- A weight balance of capacity not less than 3. kg and accuracy to 0.5 gm.
- Thermostatically controlled oven to maintain temperature of 100°C to 110°C.
- Pycnometer capacity about one litre.
- A tray of area not less than 325 cm2.
- Wash Bottle.
- Airtight Container.
SAMPLE :-
- Take aggregate sample of about 1 kg for 10mm to 4.75 mm or 500 gm if finer than 4.75mm.
TEST PROCEDURE:-
- Place the sample in a tray and cover it with water at a temperature of 22°C to 32°C.
- Keep the sample immersed for 24 ± ½ hrs.
- The water is then to be carefully drained from the sample and stirred frequently to ensure uniform drying until no free surface moisture can be seen.
- Then weigh the saturated and surface dry sample.
- A clean, dry pycnometer is taken and its empty weight is determined.
- For mineral filler, specific gravity bottle is used and the material is filled upto one-third of the capacity of bottle.
- About 1000g of clean sample is taken into the pycnometer, and it is weighed.
- Water at 27°C is filled up in the pycnometer with aggregate sample, to just immerse sample.
- Immediately after immersion the entrapped air is removed from the sample by shaking pycnometer, placing a finger on the hole at the top of the sealed pycnometer.
- Now the pycnometer is completely filled up with water till the hole at the top, and after confirming that there is no more entrapped air in it, it is weighed.
- The contents of the pycnometer are discharged, and it is cleaned.
- Water is filled up to the top of the pycnometer, without any entrapped air. It is then weighed.
- The aggregate shall be placed in the oven the shallow tray at a temperature of 100°c to 110°c for 24 ± ½ hrs. It shall Then be colled in airtight container and weight.
CALCULATIONS:-
Specific gravity, and Apparent specific gravity.
- A= Weight in gm of Pycnometer + sample and filled with distilled water.
- B= Weight in gm of Pycnometer and distilled water only.
- C= Weight in gm of saturated surface dry sample.
- D= Weight in gm of Oven dry sample.
